It is known to personalize identification cards, such as credit cards, bank cards or identity cards, by means of laser engraving. In personalization by laser engraving, the optical properties of the card material are irreversibly changed, in the form of a desired identifier, through suitable guidance of a laser beam.
For example, the identification card described in publication DE 29 07 004 includes two cover sheets and a card insert in which, through one of the two cover sheets, the personalization data are inscribed with a laser beam. To impede the reproduction of such identification cards with modern copiers, the personalization data are often introduced into metallic layers in front of a dark background. Since the metallic substrate causes a specular reflection of incident light beams, and the detector in copiers is usually disposed such that it can pick up only the diffusely scattered light from the original, the metallic surfaces and the introduced data appear all black in the copy.
Despite the recognized high security level of laser-personalized identification cards, there is a residual risk of forgery as a result of a separation of card front and card back and the resulting possible manipulation of the information located inside, such as text and image objects. In particular, after a separation of the card sheets, a metal foil located inside is counterfeitable or replaceable.
Based on that, the object of the present invention is to specify a data carrier of the kind described above having increased counterfeit security. Furthermore, it should be possible, preferably also for laypersons, to detect manipulation attempts with simple means.
This object is solved by the data carrier having the features of the claim 1. A method for manufacturing such a data carrier and a method for checking the integrity of such data carriers are specified in the coordinated claims. Developments of the present invention are the subject of the dependent claims.